Rotational evolution of pre-main sequence stars in Lupus ?

Wepresentresultsofastudyoftherotationalperiods of Post-TTauri stars (PTTSs) in the Lupus star forming region. These stars have been discovered by spectroscopic follow-up observations of ROSAT x-ray sources. Photometric observa- tions have allowed to determine their luminosity, and by com- parison with theoretical evolutionary tracks they were found to be signicantly older on average than typical TTauri stars. 46 stars have been monitored photometrically, and for 34 of them photometric variations were found that are consistent with rotational brightness modulations caused by starspots. The largenumberofdataonrotationalperiodsofpre-main-sequence (PMS)/zero-agemain-sequence(ZAMS)starsavailablebynow allows us to study the impact of stellar mass on the evolution of